1. Field of the Invention
The present invention relates to a retainer for securing a flexible tube to a barbed fitting, particularly though not exclusively for use in bio-disposable systems used in the pharmaceutical industry.
2. Description of the Related Prior Art
Fluid connections in the food, medical and pharmaceutical industries are commonly made with flanged connectors clamped to each other. The connectors have hollow spigots to which tube is connected. The flanged connectors can be made to tight tolerances, as can seals between two flanges, whereby there is little scope for stagnant accumulation at the flanges per se of material which can become contaminated, for instance by bacterial, and hence cause a problem.
However, the connection between the hollow spigot and the tubing can provide a stagnant region and thus a potential hazard. In addition, fluid leaking between the connections is lost to the process, and when using valuable fluids this can be a significant loss to the process. This arises because the nose of the connectors' spigot is tapered where it meets the tube. The latter is close to its free diameter at the small diameter end of the spigot and there is little resistance to pressurised fluid permeating between the spigot and the tube. The pressure of the fluid is liable to force the fluid right up the taper and cause a leak or at least leave a residue of fluid between the tube and the taper, and even behind the taper.
In order to minimise leakage and prevent the flexible tube from slipping off the barbed fitting tube retainers have been used. Originally, when the fittings were of metal, the retainers were jubilee clips tightened around the fitting behind the barb. When plastics material fittings came into use, cable ties became the standard method of retaining the tube on the fitting; occasionally two cable ties would be used for added security. However, while these minimise the risk of the tube being removed from the fitting, they do not prevent fluid being forced up the taper and behind the barb.
Recently the BARBLOCK® retainer has been introduced in which a collet, including a compression ring is held in position on or behind the barb with a sleeve, which locks over the collet. This again urges the tube against the fitting at a position distant from the end of the taper, and thus it is still possible for fluid to travel between the taper and the tube to the restriction point.